I'm not an MVM expert, so this may be completely wrong - but can you try changing the account used to access the DB to an SQL account? That's a good troubleshooting stpe to rule out trust issues.
Otherwise I suspect that you'll need to set up a trust relationship between the domains.
Thanks for the reply.
I think I am confused now a bit.
In ePO, the Registered Server for the local ePO server points to a remote SQL server, with Server type "ePO".
In MVM, in the Data Sources options there is an entry that points to the same remote SQL server, type "ePO" and the connection is successfully tested.
Do I need to point my data source in ePO to point to the MVM or to a remote SQL server when I'm configuring the server type "MVM"?
I'm afraid I really don't know
Hopefully another poster here uses MVM and can help...